Incandescent cathode



J. RICHTER ET AL INC-ANDESCENT CATHODE April 13, 1937.

Filed Jul 20, 1954 JOHANNES mung BERNHARD "Easel. K U R T M E 55 \NVENTQRS ATTORNEY Patented Apr. 13, 1937 UNITED STATES PATENT OFFIQE Hess, Berlin, Gesellschaft fur Berlin, Germany,

Application J My 20,

Drahtlose Telegraphic m. b. H.,

a corporation of Germany 1934, Serial No. 736,186

In Germany July 28, 1933 4 Claims.

15 sible.

In cathode ray tubes, cathodes are used for direct as well as indirect heating; in the latter at some places at which it will soon be caused to break apart.

parted, sired circular shape. The cupola of this molten pearl is subsequently covered in the known manner with a substance capable of emission for instance earth alkali oxide.

The cathodes described method are of distinct advantage overemission.

The drawing shows modes of execution of the invention by way of example. Figure 1a represents a wire I bent in the shape of a hairpin Which'may consist for instance of platinum. The wire is heated at the bend whereby the molten pearl designated by 2 in Figure 1b is formed whose cupola 3 is subsequently activated in the known manner.

In Figure 2a the wire 4 is twisted at the point 5. After melting, a cylinder 6 is formed at this place as shown in Fig. 2b, whose covering surface 1 represents the emitting surface.

Having thus described the invention, What We claim is:

1. The method of fabricating electronic emitters adapted to produce substantially point-source electronic emission, which comprises the positioning electron emitting 2. The method of fabricating filamentary electronic emitters adapted to produce substantially point-source electronic emission which comprises the steps of bending a filamentary member into 5 substantially hairpin shape, forming a loop at the apex of said bent filamentary member, heating the formed 100p portion to produce a globule thereof, and positioning electron emitting material upon a portion of the produced globule.

10 3. The method of fabricating filamentary electronic emitters adapted to produce substantially point-source electronic emission which comprises the steps of bending the filamentary member into a substantially hairpin shape, forming a plurality 15 of loops at the apex of said bent filamentary member, applying heat to the loop portions formsubstantially cylindrical bead thereof, and positioning electron emitting material upon a portion of the'produced cylindrical 4. A heated electronic emitter adapted to produce point source emission, comprising a filamentary member of substantially hairpin shape, a spherical welded bead member integral with the bight of said filamentary member, and an electron emitting material supported upon a portion of the bead member.

JOH, RICHTER. BERNH. HENSEL.

KURT HESS. 

